Heat-treating mechanism for coil springs



May'lS, 1954 M. J. NELSON ET AL 2,678,989

HEAT-TREATING MECHANISM FOR COIL SPRINGS Filed Aug. 8, 1952 4 Sheets-Sheet l Mard EWec/ZL May 18, 1954 M. J. NELSON ET AL HEAT-TREATING MECHANISM FOR COIL SPRINGS 4 Sheets-Sheet 2 Filed Aug. 8, 1952 1 0 T .w% u QW r V r m" RS mmw Ew S\ m Mm m N\ Q m NM. n mm M m mm M S 3* N v H" nuuln mun" I. W 0 v r a mm 7 HHJMM NW g L M I I g :h M W a w fimwmmwjw m a mm 3 m NM 8 Q mm \m w m mw M mm .99 km i E R w. V 3 a WW 3 ,mw Qs I QW wwfi $3 May 18, 1954 M. J. NELSON ET AL HEAT-TREATING MECHANISM FOR con. SPRINGS 4 Sheets-Sheet 3 Filed Aug. 8, 1952 INVENTORS flaw? Jl/ edsom ward firec/Za' May 18, 1954 M. J. NEL$ON ET AL HEAT-TREATING MECHANISM FOR COIL SPRINGS Filed Aug. 8, 1952 4 Sheets-Sheet 4 Patented May 18, .1954

UNITED STATES PATENT OFFICE HEAT-TREATING MECHANISM FOR COIL SPRINGS Application August 8, 1952, Serial No. 303,378

9 Claims. 1

This invention relates to a heater mechanism for heat treating coil springs and is an improvement over the heater mechanism disclosed in copending application Serial No. 235.15%, filed July 5, 1951, by Martin J Nelson and Clifford E. Ives. The heater mechanism of this invention, while of general utility, is particularly adaptable for use with a coil spring producing machine, such as disclosed in application Serial No. 700,197, filed by William E. Wunderlich on September 30, 1946, now Patent No. 2,604,202 of July 22, 1952, f or individually heat treating the coil springs as they are formed by the machine.

The principal object of this invention is to provide an improved heater mechanism for heat treating coil springs wherein the end turns of the coil springs are securely clamped and electrically contacted for passing electrical current therethro-ugh, thereby eliminating arcing and providing uniform heat treating throughout the length of the coil spring, wherein electrical current is applied to the coil spring only when the end turns thereof are securely clamped and electrically contacted, wherein the interval of time during which electrical current is applied. may be readily adjusted for obtaining the desired heat treatment of the coil springs, wherein the application of electrical. current to and the clamping and electrically contacting of the coil springs are positively and mechanically synchronized for foolproof operation, wherein the heater m.echa-' nism may be readily adjusted for accommodating coil springs having different lengths, diameters, wire gauge and the like, wherein the heater mechanism may be readily applied to coil spring producing machines for synchronous operation therewith, and wherein the heater mechanism is simple in construction, foolproof in operation and inexpensive to manufacture. The heater mechanism of this invention differs essentially from that of the aforementioned Martin J. Nelson and Clifford E. Ives copending application. in the construction of and the manner of operation of the clamping members for clamping and electrically contacting the end turns of the coil springs being heat treated. 7

Briefly, the heater mechanism of this invention includes an elongated supporting base and a shaft extending along the elongated supporting base and rotatably mounted thereon. Two spaced pairs of clamping members are provided for clamping and electrically contacting respectively the end turns of the coil spring and preferably these two pairs of clamping members are longitudinally adjustabiy secured to the support- 2 ing base and encompass the shaft. Each pair of clamping members includes a normally stationary clamping member secured to the supporting base and a movable clamping member pivotally mounted on the normally stationary clamping member. Spring means urge the movable clamping members away from the stationary clamping members. A cam for each pair of clamping members is carried by the shaft and. a cam follower on each movable clamping member engages its associated cam for moving the movable clamping members toward the stationary clamping members against the action of the spring means. A strain release connection is preferably provided between each cam follower and its movable clamping member. Means are provided for applying electrical energy to the clamping members electrically to heat treat the springs clamped thereby. Control means in cluding switch means and cam means operated by the rotatable shaft apply electrical energy to the clamping members and hence to the coil spring only when the coil sprin is securely clamped and electrically contacted by the clamping members. The control means is adjustable to regulate the time interval during which electrical energy is applied to the clamped coil springs. The rotatable cam shaft may be driven in synchronism with a coil spring producing machine for heat treating the coil springs as they are fabricated. The positions of the rotatable cam shaft and the various clamping members and cams operated thereby may be adjusted to accommodate coil springs of different lengths, diameters, wire gauges and the like.

Further objects of this invention reside in the details of construction of the heater mechanism. and the cooperative relationships between the component parts thereof.

Other objects and advantages of this invention will become apparent to those skilled in the art upon reference to the accompanying specification, claims and drawings, in which:

Fig. l is a diagrammatic illustration of a coil spring producing machine of the type disclosed in the aforementioned William E. Wunderlich application, with the heat treating mechanism of this invention applied thereto.

Figs. 2 and 3 are perspective views of the coil spring which may be heat treated by the heat treating mechanism of this invention, Fig. 2 illustrating the spring before heat treating and Fig. 3 illustrating the spring after heat treating:

Fig. 4 is a Wiring diagram of the means for applying electrical energy to the coil springs being heat treated and the control means therefor;

Fig. 5 is a. front elevational View partly in section of the heat treating mechanism of this invention, illustrating the clampin members separated for receiving a coil spring;

Fig. 6 is a top plan View of the heat treating mechanism illustrated in Fig.

Fig. '7 is an enlarged vertical sectional view through a portion of the heat treating mechanism and taken substantially along the line l-l of Fig. 6;

Fig. 8 is a partial sectional view corresponding to the right hand portion of Fig. l but illustrating a coil spring clamped by the clamping members for heat treating the coil spring;

Fig. 9 is an end elevational view look the left of Figs. 5 and 6;

Fig. 10 is a ve'tieal sectional view taken substantially along the line ii-li of Fig. 7;

Fig. 11 is a vertical sectional view taken substantiaily along the line il-li of Fig. 7;

Fig. 12 is a view illustrating the position of th 1 left end of the coil spring as illustrated in Fig.

ing from i) as it is clamped by the left hand clamping members;

Fig. 13 is a view similar to Fig. 12 but illustrating the position of and the mane. r in which the right end of the coil spring as illustrated in Fig. 5 is clamped by the right hand clamping members;

Fig. la is an exploded perspective view of the left hand clamping members;

Fig. 15 is an enlarged sectional view through the electrode portion of the left hand clamping members;

Fig. 16 is an exploded perspective view of the parts forming the electrode portions of the left hand clamping members.

Referring first to 2 and 3, a coil spring to be heat treated is generally designated l0. includes a plurality of inner convolutions or turns ii, and a pair of end turns it to 'minating in knots it. The coil spring be plain as illustrated. or the ends thereof may be clamped or offset, as desired. When the coil spring originally fabricated, the knots it are located out of line as illustrated in 2, so that when the coil spring is heat treated the knots i3 line up as illustrated in the heat treating of the coil spring causing a twisting within the coil sprin Any suitable machine may be utilized for the purpose of fabricating the coil s Hi and for purposes of illustration in this application Fig. l discloses coil spring producing machine generally designated at l? which may be of the type disclosed in the aforementioned William E. Wunderlich application. The machine l5 in cludes a base or standard it? and a coiling mechanism ii for coiling wire into the double ended coil spring iii. when the coil spring it is thus formed is grasped by fingers it carried by radial arms 58 of a transfer chanism 26 which is intermittently rotated in a counterclockwise direction as illustrated in Fig. 1. The coil springs Hi thus formed and grasped by the tingers it! are advanced to a knotting mechanism wherein one end of the coil spring it is knotted as at it and, if desired, crimped into an offset. The coil springs iii are then advanced to a second knottin mechanism wherein the other end of the coil spring is knotted and may also be crimped into an oilset if so desired. The knotted coil springs is are then advanced by transfer mechanism to the heat treating inechanism of invention, generally designa 23. After the coil springs it are heat treated they are advanced by the transfer mechanism to a stacker mechanism wherein the heat treaeted coil springs are stacked in nested form. Since the coil spring producing machine diagrammatically illustrated in l iully disclosed in the aforementioned Winiarn .Wunderlich application a further description thereof is not considered necessar The heat treating mechanism 23 of this in vention includes an elongated supporting base 26 in the form of an angle member which is secured to the standard or support it of the coil spring producing machine by means of bolts 21. The upwardly extending leg of the supporting base 2'6 is provided adjacent its ends with a pair of vertically arranged slots A pair of bearing blocks and 39 are vertically adiustably secured to the supporting base 26 by screws 3! extending through the slots 28. A rotatable cam shaft 32 is rotatably journaled by bearings 33 and 3G in the bearing blocks 2s and 36 respectively, the shaft 552 extending longitudinally along the supporting base By reason of the vertical slots 25E, the bearing blocks manure and hence the cam shaft 5%? may be vertically adiustably positioned as desired. A barE-ll extending along the shaft 32 is secured to the bottoms of the bearing blocks 29 and 35 by means of bolts 38. This bar 37 is located forwardly of the supporting base 23 and is provided with a longitudinally arranged slot The shaft 32 is maintained in proper longitu dinal position by means of collars 4i and 52 secured to the shaft 32 on opposite sides of the bearing block 36. The end of the shaft 32 carries a flanged hub 43 which is secured to shaft by means of a key is and set screw. A gear 45 is secured tothe flange of the hub it by screws 66. The gear meshes with a driving gear 47 secured to a shaft 48 which drives the knotting mechanism 22. The shaft makes one complete revolution in its operation of the knotting mechanism 22 and this is done during each cycle of operation of the coil spring producing machine. The gear 35 is preferably twice the size of the driving gear l"! so that during each cycle of operation of the coil spring producing machine [5 the rotatable shaft 32 of the heater mechanism is driven through one lialz" a revolution.

The heater mechanism of this invention includes a pair of clamping members, each pair including a stationary clamping member 5t having a slide portion 5| resting on the longitudinal bar 37. Projections 53 extend downwardly from the slide portion 51 on either side of the bar 3i for maintaining alignment thereof. A screw 54 extends through the slot 39 in the bar 3? for adjustably securing the stationary clamping member 5!] in proper position on the bar 31. The stationary clamping member is provided with a hole 55 for encompassing the shaft 32 and with a slot 56 extending downwardly from the hole 55. It is also provided with a transverse bore 5''! communicating with the slot 56. The slot 56 is provided for the purpose of receiving and mounting a movable clamping member having an extension til extending through the slot 56. The movable clamping member 59 is provided with ahole '6! for encompassing the shaft 32. The extension till is provided with a i. not; sit

transverse bore 62 for receiving a pivot pin 83 for pivotally mounting the movable clamping member 59 to the stationary clamping member 50. The stationary clamping member 50 and the movable clamping member 59 are each provided with a pair of sockets (i l and 65 respectively for receiving a pair of compression springs 66, the compression springs urging the movable and stationary clamping members apart as illustrated in Figs. 5 to 7. The clamping members are moved toward each other against the action of the springs 66 to clamp the end turns l2 of the coil springs therebetween as illustrated in Fig. 8.

The extension 68 of the movable clamping member 59 is hollowed out at 68 and is provided at its end with a bore 69. It is also provided with an opening in the bottom thereof. A cam follower member ll having a bore E2 therein is pivotally mounted in the hollowed portion 53 of the extension 50 by means of a pivot pin "it extending through the bores 53 and I2. A cam follower 14, preferably of the antifriction type, is secured to the end of the cam follower member II by means of a screw 15. The cam follower member H carries a stud 16 which extends downwardly through the opening H3 and which carries at its lower end nuts ll. A spring i8 is interposed between the extension 60 and the nuts 11 for urging the cam follower l4 upwardly. The amount of upward movement of the cam follower 14 with respect to the extension iii is limited by a stop screw 19 carried by the extension 60 and locked in place by a lock nut 80. The spring 58 and the stop screw 19 operate to position the cam follower M with respect to the extension 69 of the movable clamping member and also to provide a strain release connection therebetween.

A pair of cams 8! is secured to the shaft 32. for engaging the cam followers 75 for operating the movable clamping members 59 against the action of the springs 66. These cams iii are keyed to the shaft 32 by means of keys $3 located in key slots 82. The key slots 82 are elongated so that the cams 8! may be adjustably positioned along the shaft 32 and the cams 8! may be locked in desired adjusted position by means of set screws 84. The cams 8i operate pivotally to move the movable clamping members 59 towards the stationary clamping mem bers 58 to provide a positive clamping action on the end turns E2 of the coil springs l5 and the extent of the clamping action may be regulated by adjusting the nuts ll on the stud it. If a coil spring should be improperly inserted between the stationary and movable clamping members, as for example, the knot l3 being interposed between the clamping members, then the spring is is compressed to allow pivotal movement of the cam follower member I! with respect to the movable clamping member 59 to provide an efiective strain release connection and to prevent breakage of the apparatus under these conditions. The cams 8! are preferably double cams and are rotated through 180 de grees during each cycle of operation of the coil spring forming machine I5. When the clamping members are adjusted along the supporting base 26 for accommodating coil springs of different length, the cams 81 are correspondingly adjusted along the shaft 32. This provides for simple adjustment of the heat treating mechanism for various length coil springs.

Referring more particularly to Figs. is to 1%. the upper ends of the clamping members iii! and 59 are provided with transverse recesses 53 and 89 and holes 90 and 9| respectively. These are utilized for the purpose of securing in place the electrodes for electrically contacting the clamped coil springs. The recess 88 of the stationary clamping member 50 receives an angular electrical insulating member 92 which is provided with holes 93 and a flared extension. In turn, the angular electrical insulating member 92 receives an angular electrical metallic wear plate 94 which in turn receives an angular electrical insulating member 95 having holes at. This angular electrical insulating member 95 receives an electrode 97 having tapped holes 98 and a flared extension 9%. One end of a metallic strap Hill is secured along with an electrical terminal it! to the electrode 9'1 by means of a screw I92. In alike manner, the recess 89 of the movable clamping member 53 receives an angular electrical insulating member 183 having holes H14, an angular metallic wear plate I05, an angular electrical insulating member 1% having holes 591 and an electrode we having tapped holes Hi9 and a flared extension H0. Here the other end of the strap Hit is secured to the electrode I08 by means of a screw Hi. The parts 92, 94, E35, and ST are secured to the stationary clamping member 59 by means of a pair of screws E E3 which are insulated from the clamping mem-v ber 56! by means of an electrical insulating sleeve H2. In a like manner the parts H33, I05, I86 and IE8 are secured to the movable clamping member as by a pair of screws H5 which in turn are insulated from the movable clamping member 5% by means of insulating sleeves lid. Thus, when the end turns of the coil springs are clamped between the stationary and movable clamping members, they are firmly electrically contacted by the electrodes 9? and lot for the purpose of passing electric current therethrough for heat treating the same, the electric current being applied to the electrodes 9'! and 68 through the electrical terminals 3i and the metallic straps Hit. The metallic wear plates 94 and liii'a and their associated insulating members 95 and H36 prevent electrical contact with the intermediate turns l I of the coil springs and also operate to prevent wear of the electrical insulating members. Since in the operation of the heat treating mechanism of this invention the inner convolutions H or" the coil springs might engage the electrodes at only one point as illustrated more clearly in Figs. 5, 7, 8, l2 and 13, only one of the electrodes need be provided with the overlying electrical insulating members and metallic wear plates. However, for uniformity all of the electrodes may be provided with this protective arrangement if desired. The flared ends 99 and lie of the electrodes 9? and it are for the purpose of facilitating the insertion of the end turns E2 of the coil springs between the two pairs of clamping members 55. and 59.

A spacer block 253 is secured to the inside of the bearing block and it has secured thereto by means of screws 222 a normally open switch I2! which is provided with a cam follower I23. A cam 52 3 having a pair of lobes N5 is secured to the shaft 32 by means of a set screw I25. As the shaft 32 is rotated the lobes 25 of the cam we operate the cam follower i23 for momentarily closing the normally open switch 25. The cam 62 3 is so positioned on the cam shaft 32 that the switch i2! is momentarily closed only after the clamping members 58 and 59 have securely clamped. the end turns 12 of the coil to be heat treated.

A plate I 28 is. rotatably, mounted on the shaft bearing '331on1t'he. outside. or the bearing block 291. 'An outer plate 129. is secured at its lower endthrough a spacer 130, and screws I3! to the lower end of the plate I28. A handle I32 is carried. by a stem I33 which in turn is welded to the plate I29 for rotating the plates I and i28 about the shaft 32. The upper end of the plate I28 is provided with a slot I34 for receiving a screw I35 for'adjustably locking the plate I28 in any desired rotative position. The upper endlof the plate I28 may also be provided with suitable indicia I35 forindicating the rotative position of the plate. A normally closed switch I31issecured to the plate I23 by screws I38 and itis. provided with a cam follower I39 engaging a ,cam Mil having high lobes MI, the cam l lil being secured to the shaft 32 by a set screw I 42. When one or the other of the lobes E li of the cam M9 engages the cam follower the switch I31 is momentarily opened. By moving the handle M2, the plate I28, and the switch m3 are correspondingly moved about the of the cam shaft 32 so that the switch E31 may be momentarily opened at various points in the rotation of the cam shaft 32, depending upon the adjustment of the switch carrying plate Thus, the time at which the switch. :31 is momentarily opened with respect to the time at which the switch .I2I is momentarily closed may be adjusted at will by manipulation of the handle I32.

Electrical energy is applied to the electrodes 91 and I08 of the clamping members 5% and 59 and hence to the. coil spring clamped thereby by means of a low voltage high current transformer which is designated generally at :56 in Fig. 4. This transformer is of conventional construction and has a primary I5! and a secondary 52, the secondary 152 being connected by suitable leads. I53 to the electrical connectors iill carried by the electrodes 91. Electrical energy is supplied to the primary l5I of the transformer by means of conductors I54 and IE5 leading from some source of power not shown. The application of electrical energy to the primary I5I of the transformer I55 is controlled by a relay having an operating coil I5fi for operating switches I51, I58 and i59. When the relay coil i is energized, the switches I51, I58 and I52 are closed and when the relay coil I55 is deenergized these switches are opened. The switches Hi1 and I58 control the application of electrical energy to the transformer primary l5l, so that when the relay is energized electrical energy is applied to the transformer and when it is deenergized the application of electrical energy is interrupted. The switch I59 of the relay operates to complete a maintaining circuit for the relay.

The relay winding I56 is controlled by the normally opened switch I2I and the normally closed switch 131 operated by the cam shaft 32. It may also be controlled by a switch it! and a start and stop switch I62. The switches I62, I31 and I2I are connected in series with the relay coil I55 and the relay switch I59 is connected in shunt with the normally open switch I2I. In order to energize the relay coil I55, the switches ISI, I62, I31 and I2! must be closed and. the relay may be maintained energized through the switches I61, I62, I31 and I53 independently oi the switch I2I until switch I31 or. switches IGI and I62 are opened.

' Assuming that theswitches I'6I and I62 are var 8. closed and .thatthe coil spring producing: machine is in operation with a coil spring to be-heat treated moved between the clamping members and 59 and securely clamped'therebetween, normally opened switch I'2I. is thereafter closed to complete a circuit from the conductor through switches. I6i, I62, [31,. I21 and relay coil to the conductor I54. This energizes the relay coil for closing the switches .I51,,,I5 8 and Closure of the switchesI51 and I58 ap-. plies electrical energy to the transformer I5.0..and hence causes electrical current tocoursethecoil spring as for heat treating the same. ,Closure of the switch I59 upon energization of the relay coil completes a maintaining circuit for therelay coil I 56 independent of theswitch I2I so that when the switch IZI opens after being momentarily closed, the relay coil I56 remains energized. further rotation of the cam-shaft. 32,,the normally closed switch i31 is opened at a point in the cycle depending upon the adjustment of the switch with respect to the cam shaft 32. ,,Up. on opening of this switch I31, the maintaining circuit to the relay coil 55 is broken and the re,- lay becomes deenergized for opening the switches 551, I53, and I59. Opening of the switches I51 and i563 interrupts the application of electrical energy to the coil spring it] being heat treated. Opening of the switch I59 of the relayprevents the relay from again being energized until Such during the next cycle of operation. Thus, .elec-. trical energy is applied to each coil spring clamped between the clamping members 50.and

and the interval of time at which the electrical.

energy is so applied is dependent upon the adjustment of the normally closedswitch I31 In all instances, electrical energy is applied to the electrodes 91- and 108 only when the end ,turns I2 of the coil spring are securely clamped by the clamping members 50 and 59. By adjustingthe normally closed switch I31, the amount .of heat treatment applied to .each coil spring maybe regulated at will.

An indicating lamp I63 may be connected across the conductors I54 and I 55 toindicate that the heat treating mechanism is .in condition for operation and an indicating lamp I64 maybe connected across the primary .I5I of .the trans former :59 for indicating the periodof applica tion of electrical energy to the coil spring being heat treated.

The switch ISI in series with the relay coil;

556 is operated by the clutch mechanism of the coil spring producing machine I5, so thatthe relay may be energized and electrical energy applied to the electrodes of the clamping members only when the coil spring producing machine is spring when the coil spring producing machine is shut down. The start and stop switch I62 is conveniently located on the coil spring producing machine I5 so that the application of electrical energy through the electrodes of the heat treatme; mechanism may be interrupted atthe willof the machine operator.

While for purposes of illustration one form of this invention has been disclosed, other forms thereof may become apparent tothose skilled in the art upon reference to this disclosure and, therefore, this invention is to belimited' only by the scope of the appended claims. .7

We claim as our invention:

1. A heater mechanism for hcattreatingcoil as "re normally opened switch I2] is'closed springs comprising, an elongated supporting base, a shaft extending along the elongated supporting base and rotatably mounted thereon, two spaced pairs of clamping members for clamping and electrically contacting respectively the end turns of a coil spring, each pair of clamping members including a normally stationary clamping member secured to the supporting base and a movable clamping member pivotally mounted on the normally stationary clamping member, a cam for each pair of clamping members carri d and rotated by the shaft, and a cam follower on each movable clamping member and engaging its associated cam for moving the movable clamping members with respect to the normally stationary clamping members.

2. A heater mechanism for heat treating coil springs comprising, an elongated supporting base, a shaft extending along the elongated supporting base and rotatably mounted thereon, two spaced pairs of clamping members for clamping and electrically contacting respectively the end turns of a coil spring, each pair of clamping members including a normally stationary clamping member longitudinally adjustably secured to the supporting base and a movable clamping member pivotally mounted on the normally stationary clamping member, a cam for each pair of c1amping members carried and rotated by the shaft, and a cam follower on each movable clamping member and engaging its associated cam for moving the movable clamping members with respect to the normally stationary clamping members.

3. A heater mechanism for heat treating coil springs comprising, an elongated supporting base, a shaft extending along the elongated supporting base and rotatably mounted thereon, two spaced pairs of clamping members for clamping and electrically contacting respectively the end turns a coil each pair of clamping members including a normally stationary clamping member encompassing the shaft and longitudinally adjustably secured to the supporting base and a movable clamping member encompassing the shaft and pivotally mounted on the normally stationary clamping member, a cam for each pair of clamping members carried and rotated by the shaft, and a cam follower on each movable clamping member and engaging its associated cam for moving the movable clamping members with respect to the normally stationary clamping members.

A heater mechanism for heat treating coil springs comprising, an elongated supporting base, a shaft extending along the elongated supportmg base and rotatably mounted thereon, two spaced pairs of clamping members for clamping and electrically contacting respectively the end turns of a coil spring, each pair of clamping members including a normally stationary clamping member secured to the supporting base and a movable clamping member pivotally mounted on the normally stationary clamping member, a cam for each pair of clamping members carried and rotated by the shaft, a cam follower on each movable clamping member and engaging its associated cam for moving the movable clamping members with respect to the normally stationary clamping members, and a strain release connection between each cam follower and its movable clamping member.

5. A heater mechanism for heat treating coil springs comprising, an elongated supporting base, a shaft extending along the elongated supporting base and rotatably mounted thereon, two

spaced pairs 01" clamping members for clamping and electrically contacting respectively the end turns of a coil spring, each pair of clamping members including a normally stationary clamping member encompassing the shaft and longitudinally adjustably secured to the supporting base and a movable clamping member encompassing the shaft and pivotally mounted on the normally stationary clamping member, a cam for each pair of clamping members carried and rotated by the shaft, a cam follower on each movable clamping member and engaging its associated cam for moving the movable clamping members with respect to the normally stationary clamping members, and a strain release connection between each cam follower and its movable clamping member.

6. A heater mechanism for heat treating coil springs comprising, an elongated supporting base, a shalt extending along the elongated supporting base and rotatably mounted thereon, two spaced pairs of clamping members for clamping and electrically contacting respectively the end turns of a coil spring, each pair of clamping members including a normally stationary clamping member secured to the supporting base and a movable clamping member pivotaily mounted on the nor mally stationary clamping member, spring means for urging each movable clamping member away from its stationary clamping member, a cam for each pair of clamping members carried and rotated by the shaft, and a cam follower on each movable clamping member and engaging its associated cam for moving the movable clamping members toward the stationary clamping members against the action of the spring means.

"I. A heater mechanism for heat treating coil springs comprising, an elongated supporting base, a shaft extending along the elongated supporting base and rotatably mounted thereon, two spaced pairs of clamping members for clamping and electrically contacting respectively the end turns of a coil spring, each pair of clamping members including a normally stationary clamping member secured to the supporting base and a movable clamping member pivotally mounted on the normally stationary clamping member, spring means for urging each movable clamping member away from its stationary clamping member, a cam for each pair of clamping members carried and rotated by the shaft, a cam follower on each movable clamping member and engaging its associated cam for moving the movable clamping members toward the stationary clamping members against the action of the spring means, and a strain release connection between each cam follower and its movable clamping member.

8. A heater mechanism for heat treating coil springs comprising, an elongated supporting base, a shaft extending along the elongated supporting base, a shaft extending along the elongated supporting base and rotatably mounted thereon, two spaced pairs or clamping members for clamping and electrically contacting respectively the end turns of a coil spring, each pair of clamping members including a normally stationary clamping member encompassing the shaft and longitudinally adjustably secured to the supporting base and a movable clamping member encompassing the shait and pivotally mounted on the normally stationary clamping member, spring means for urging each movable clamping member away from its stationary clamping member, a cam for each pair or clamping members carried and rotated by the shaft, and a cam follower on each movable clamping member and engaging its associated cam for moving the movable clamping members toward the stationary clamping members against the action of the spring means.

9. A heater mechanism for heat treating coil springs comprising, an elongated supporting base, a shaft extending along the elongated supporting base and rotatabiy mounted thereon, two spaced pairs of clamping members for clamping and electrically contacting respctively the end turns of a coil spring, each pair of clamping members including a normally stationary clamping member encompassing the shaft and longitudinally adjustably secured to the supporting base and a movable clamping member encompassing the shaft and pivotally mounted on the normally stationary clamping member, spring means for urg- References Cited in the file of this patent UNITED STATES PATENTS Name Date Zimmerman July 19, 1938 Number 

